Plants grown is a standard hydroponic system go through a period of vegetative growth that lasts 4 weeks, followed by a period of flowering growth that lasts 8 – 10 weeks. Total grow time from clone to harvest is approximately 12 – 14 weeks.
There are 14 essential minerals in fertilizers that plants require for life. Macro nutrients are used by plants in the highest amounts. Micro nutrients are used in smaller amounts but are still required for life.

Water by itself is not enough to feed your plants. Water contains some native minerals but not enough, or all the required minerals. Fertilizer supplements containing all 14 essential minerals must be added to your water to create a feeding solution.
Hydroponic plants require a very precise application of fertilizer. Dosages vary from week to week, supplying plants ideal nutrition for their stage of growth, while avoiding excesses that cause toxifying salt buildups in the grow media.
In a hydroponic system, there are specific fertilizers designed to provide all the essential minerals required for plant growth – except sometimes calcium and magnesium which may require a separate product. These fertilizers are typically labeled for specific weeks of plant growth and contain precise proportions of minerals tailored to meet the exact requirements of each growth stage. For instance, a fertilizer labeled for Weeks 1 & 4 may contain more phosphorus during the first week of growth to support root strike and during the fourth week to initiate budding. The goal of using these hydroponic fertilizers is to provide the exact nutrients plants need for the indicated weeks of growth to ensure healthy and optimal plant development.
Calcium and Magnesium is a separate product from all the other minerals for reasons explained here.